The resonant detection of subterahertz radiation by two-dimensional electron plasma confined in a submicron gate GaAs/AlGaAs field-effect transistor is demonstrated. The results show that the critical parameter that governs the sensitivity of the resonant detection is omegatau, where omega is the radiation frequency and tau is the momentum scattering time. By lowering the temperature and hence increasing tau and increasing the detection frequency omega, we reached omegatausimilar to1 and observed resonant detection of 600 GHz radiation in a 0.15 mum gate length GaAs field-effect transistor. The evolution of the observed photoresponse signal with temperature and frequency is reproduced well within the framework of a theoretical model. (C) 2002 American Institute of Physics.